Seaweeds harvested from both cultivated farms and wild stocks are primarily used as human food particularly in Asian countries such as Japan, China and Korea. Seaweeds are also used as a source for production of phycocolloids, phytosupplements (soil additives, fertilizers), pharmaceuticals, nutraceuticals and cosmetics. Phycocolloids, with global market value over USD 1 billion are the second major commercial product extracted from seaweeds after edible seaweed market.
Bixler and Porse in the article entitled “A Decade of Change in the Seaweed Hydrocolloids Industry”, J. Appl. Phycol. 23, 321-335 (2011) presented a detailed account on production of hydrocolloids (agar, alginates and carrageenan) and trade value from 1999-2009 by world seaweed industry and estimated that production in 2009 was 86,100 dry tons and value as over USD 1.0 billion. All these seaweed industries used whole dry biomass as raw material for extraction of hydrocolloids alone and the leftover solid waste remaining after extraction was used for agricultural applications.
Recently Kumari et al. in Fatty acid profiling of Tropical Marine Macroalgae: An Analysis from Chemotaxonomic and Nutritional Perspectives, Phytochemistry, 86, 44-56 (2013) analyzed a wide range of tropical seaweeds for fatty acids and reported occurrence of good amounts of polyunsaturated fatty acids (PUFAs), and further suggested their possible supplementation in nutraceuticals and foods. This study exclusively dealt with fatty acids analysis from the perspective of taxonomy and nutritional value alone and did not report analysis and extraction of other components present in the biomass.
Pangestuti and Kim in Biological activities and health benefit effects of natural pigments derived from marine algae, J. Funct. Foods. 3: 255-266 (2011) presented a great deal of information on health beneficiating effects of functional ingredients particularly pigments from marine algal sources. This article exclusively focused on biological activities of marine algae-derived natural pigments and emphasized their potential applications in foods as well as pharmaceutical areas but did not make any attempt to report extraction of other products extracted in the present invention.
Kumar and Sahoo in Effect of seaweed liquid extract on growth and yield of Triticum aestivum var. Pusa Gold, J. Appl. Phycol. 23: 251-255 (2011) demonstrated beneficial effects of foliar spray of seaweed liquid extract from brown seaweed Sargassum wightii on growth and yields of rice variety Pusa Gold. This article also describes the preparation of seaweed liquid extract but did not report extraction of other products from the seaweed as mentioned in the present invention.
Meena et al. in Preparation of superior quality products from two Indian agarophytes, J. Appl. Phycol. 23: 183-189 (2011) described a method for recovery of superior quality agar having gel strength from 250 to 2000±50 g cm−2 form Gelidiella acerosa and Gelidium pussillum of Indian waters following pretreatment of sample with acid and alkali. However, native agars obtained from the above seaweeds without alkali pretreatment yielded gel strength in the range of 250 to 800±25 g cm−2. The drawback of their process is 1) pretreatment of sample with acid and alkali and 2) the entire biomass was processed for production of agar alone and not for other bioproducts as described in the present invention.
Meena et al. in Preparation, characterization and benchmarking of agarose from Gracilaria dura of Indian waters, Carbohyd. Polym. 69: 179-188 (2007), reported a low gel strength native agar (270±10.84 g cm−2) from G. dura without alkali pretreatment. However, they subsequently prepared a superior quality agarose from the same seaweed by alkali pretreatment of sample which in turn resulted in increase of gel strength ranging from 280 to 2200 g/cm2. However, this study also describes a process aimed at the recovery of only a single product from feedstock ignoring other ingredients of commercial value.
Prasad et al. in Superior quality agar from red alga Gelidiella acerosa (Gelidiales Rhodophyta) from Gujarat coast of India: An evaluation, Indian J. Mar. Sci. 35: 268-274 (2006), disclose a process for preparation of agar having gel strength in the range of 200 to 700 g cm−2 from a red seaweed G. acerosa from west coast of India. However, their process employed an acid pretreatment of sample, thus yielding a low quality agar in terms of gel strength in contrast to the present invention.
Prasad et al. in Agars of Gelidiella acerosa of west and southeast coasts of India, Bioresour. Technol, 98: 1907-1915 (2007) reported the preparation of agar with gel strength ranging from 450 to 845 g cm−2 form G. acerosa from west coast of India. However, this process also used an acid pretreatment and obtained single product despite having possibilities to produce multiple products from feedstock.
Shukla et al. in Partial characterization of sulfohydrolase from G. dura and evaluation of its potential application in improvement of the agar quality, Carbohyd. Polym. 85: 157-163 (2011), disclose the enhancement of commercial agar gel strength to 486 g cm−2 from 190 g cm−2 by the in situ catalytic application of sulfohydrolase. However, the gel strength was still lower than that achieved in the present invention.
E. Marinho-Soriano in Agar polysaccharides from Gracilaria species (Rhodophyta, Gracilariaceae), J. Biotechnol. 89: 81-84 (2001) described extraction of agar polysaccharides from different species of Gracilaria (Rhodo phyta, Gracilariaceae) including Gracilaria dura, using hot water extraction at 110 degree C. for 1 hr, without any pretreatment of the seaweed. The gel strength of G. dura agar was 318 g cm−2. However, this method also deals with extraction of a single product from feedstock despite having possibilities to prepare multiple products.
Mihranyan et al. in Moisture sorption by cellulose powders of varying crystallinity, Int. J. Pharm. 269: 433-442 (2004), disclosed the method for cellulose extraction. However, the major drawback of this process is the defatting of biomass prior to cellulose extraction, and prolonged process duration.
Siddhanta et al. in Profiling of cellulose content in Indian seaweed species, Bioresour. Technol. 100: 6669-6673 (2009), reported the cellulose contents of several seaweeds from Indian water. However, the cellulose profiling method included defatting of biomass prior to cellulose extraction, use of excessive chemicals and time consuming.
Bligh et al. in A rapid method of total lipid extraction and purification, Can. J. Biochem. Phys. 37(8):911-915, (1959), disclosed a method for the extraction of only lipids from biomass and made no effort to isolate other ingredients from biomass.
Sampath-Wiley et al. in An improved method for estimating R-phyoerythrin and R-phycocyanin contents from crude aqueous extracts of Porphyra (Bangiales, Rhodophyta), J. Appl. Phycol. 19:123-129 (2007), described the method for the extraction and estimation of pigments in the red seaweed Porphyra sp. However, they did not report the extraction of other products as described in the present invention.
Kumar et al. in Bioethanol production from Gracilaria verrucosa, a red alga, in a biorefinery approach, Bioresour. Technol, 135:150-156 (2013), successfully demonstrated agar and bioethanol production from algal waste (rich in holocellulose) that remained after agar extraction from Gracilaria verrucosa (Hudson) Papenfuss. However, this process deals with production of two products only and also used dry biomass preventing realization of other products.
Mondal et al. in Fuel intermediates, agricultural nutrients and pure water from Kappaphycus alvarezii seaweed, RSC Advances. 3:17989-17997 (2013), described an integrated method for the preparation of fuel intermediates, agricultural nutrients and pure water from the red seaweed Kappaphycus alvarezii. However, in this process extensive in situ chemical conversions aided by catalysts from external sources were employed for achieving satisfactory yield and quality of products, whereas the present invention does not include any external catalysts.
Rideout et al. in U.S. Pat. No. 5,801,240 reported the method for extracting the semi refined carrageenan from seaweed. However, the process was specific to recover a single product. The present invention on the other hand describes the process for the recovery of refined carrageenan along with the several byproducts such as natural pigments, lipid, minerals and bioethanol from fresh seaweed biomass.
Eswaran et al. in U.S. Pat. No. 6,893,479 described an integrated method for production of carrageenan and liquid fertilizer from fresh seaweeds. However, the limitation of this process is that it provides only two products from fresh biomass as initial starting material ignoring the rest of the spectrum of products as isolated in the present invention.
Mody et al. in Patent US 2013/0005009, described a process for integrated production of ethanol and seaweed sap from Kappaphycus alverezii. This process also demonstrated recovery of maximum of two products only from feedstock. The major drawbacks of this process was that the carrageenan fraction was targeted for bioethanol production which is an important marketable polysaccharide and the process also includes acid treatment for hydrolysis as contrary to the present invention.
Baghel et al. in Characterization of agarophytic seaweeds from the biorefinery context, Bioresour. Technol, 159: 280-285 (2014) reported quantification of various components of biomass such as natural colorants (R-phycoerythrin (R-PE), R-phycocyanin (R-PC)), minerals, proteins, lipids, cellulose and agar in a range of red seaweeds and suggested their possible extraction in order to develop seaweed biorefinery, however authors did not report any scheme or process useful for biorefinery.
In short, it may be summarized that most of the processing technologies developed so far for recovering valuable products from seaweeds are aimed at extracting only one or two products at a time as well as utilize chemical conversions through catalytic routes for transformation of various natural products into high value products.
Thus, keeping in view the drawbacks of the hitherto reported prior art, the inventors of the present invention realized that there exists a dire need to provide a holistic approach to derive a spectrum of bioproducts such as natural colorants, total lipids, phycocolloids, cellulose and nutrient rich liquid product of commercial value from fresh seaweeds, wherein the process ensures complete utilization of raw materials without leftover solid waste, while simultaneously reusing the solvents utilized for two to three successive cycles without compromising on the quality of the successive products.